Improved turn-table



'NITED STATES PATENT OFFICE.

JAMES K. THOMPSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO HIMSELF AND WILLIAM B. HOWARD, OF SAME PLAGE.

IMPROVED TU RN-TABLE.

Specification forming part of Letters Patent No. 78,553, dated J une 2, 1868.

To all whom t may concern:

Be it known that I, JAMES K. THOMPSON, of the city of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Turn-Tables; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, making part of this specification, and to the letters of reference marked thereon, like letters indicating like parts .wherever they occur.

To enable others skilled in the art to construct and use my invention, I Will proceed to describe it.

In the accompanying drawings, Figure l represents a side elevation, and Fig. 2 a plan, oi' the turn-table, and Fig. 3 a side elevation and a section of a part of the bearing-circle, made of boiler and angle iron.

My improvements in turn-tables are intended principally to be used for draw-bridges,

although, with proper modifications, they can `be used in railroad or any other turntables;

and their nature consists in a bearing-frame placed on the bearing-wheels and moving around the pivot of an ordinary spider, said frame consisting of a bearing-circle, strengthcned by two crossbeams, on the top of which circle and beams are placed several trussed bearing-beams, on which rests the bridge.

A is a pier; B, gear-circle; C, circular track; D, spider; d, center-plate of spider; E E, bearing-wheels; F, the step, and f the pivot.

The bearingframe G, supporting and movin g the bridge, is placed on the bearing-Wheels E, and has pivot j' for its center. It consists,

irst, of bearing-circle H, made of I-beam iron, or of boiler-iron and angle-iron combined, as on Fig. 3, the last forming the flanges h h, riveted to the boiler-iron. The circle is strengthened by cross-beams 7c k, made ot' I-beam iron, and secured to the circle H by bent platesl l, bolted to the beams and the bearing-circle. A plate, mwith an opening to lit pivot j', is placed in the center of the circle H, underneath beams k k, to Which it is bolted; second, of the trussed bearing-beams M M, made of I-beam iron, the centralbeam being double. Thesebeams are trussedfor the purpose of having them stiffened. The truss of each beam consists of two tension-rods,m m, placed on one side of thebeam, and passin g over one or two supporting-plates, P Il, made of beam-iron, and placed across beams M M in their middle.

The rods are secured, by nuts a fn', to the iianged cast-iron plates or shoes N N, placed over the end of the beams, through which shoes the ends of said rods pass.

The bearing-beams M M are secured to the beams 7c 7c by stirrups or bolts. There is a fork, Q, secured to the circle H and bearingshaft R, anda pinion, S, gearing into the gear-circle B, the shaft passing through the iiooring of the bridge, and worked by an ordinary key.

The chords of the bridge are laid on the beams M M, to which they are secured by stirrnps or bolts.

The advantages of my turn-table consist in its easy working, in the strength and durabilityof the structure, and in the economy of construction on account of the simplicity of the arrangement.

What I claim as my invention, and desire to secure by Letters Patent, is

The bearing-frame G, consisting of bearingoircle H, cross-beams k k, and trussed bearingbeams M M, each ofthe above said parts constructed as described, and the whole arranged and operating substantially as and in the manner herein set forth and specied.

JAMES K. THOMPSON.

Vitnesses:

J. B. TURGHIN, N. K. KRonBnR. 

